How is nitrogen used in welding and metalworking?

In the metals industry, nitrogen is utilized in welding, soldering, and brazing processes to serve as a protective, nonreactive atmosphere. By displacing oxygen and moisture, it helps prevent undesirable chemical reactions such as oxidation, carburization, and decarburization during these operations.1

Beyond its role in joining metals, nitrogen is also used in a process known as nitriding. This is a surface hardening technique where nitrogen is introduced into the surface of steel objects. By heating the steel in gaseous ammonia or through ion (plasma) bombardment, the nitrogen combines with iron and other alloying elements to form hard metallic nitrides, significantly increasing the surface hardness of the material.2